Regardless of the type of metal coatings, which are attached to a layer of such as oxide chemical substance, is mentioned in the previous contact deformation actually refers to these oxides deformation. As for the surface oxide film, whether it is mentioned in the beginning or in the connector application, are the contact interface of the adverse factors. Choosing the right contact plating to generate oxide plays a decisive role, not only decided to film type also may determine its damaged easily degree. This topic will be discussed in more detail in chapter third.

If the surface oxide film and without removing or only partially be eliminated, the result will lead to additional compression resistance and the last resistance. Oxide film resistor can exist in two forms, as shown in figure 2.15. If the oxide film is not eliminated, with compression resistance generation will produce oxidation resistance. If the film is partially removed, the oxidation resistance will become effective resistance and metal compression parallel resistance (such as 2.15 of the right hand side ). The high impedance of the oxide film resistor due to metallic contact conduction and to effectively reduce the thickness. However, overall speaking, the resistance value is increased, the reason is the presence of oxide film with reduced metal contact area.

Surface oxide induced telecommunications debilitating. Oxide resistance coefficient can be very high, equivalent to the semiconductor to the insulator resistance coefficient range, and has a high degree of variability. Oxide variability can occur in the following three compound properties:

Ingredients.

The structure.

The thickness.

These three properties, with the oxide film forming conditions. Especially the environmental component, temperature, humidity on the film structure, performance plays a decisive role. Oxide film due to the variability of the oxide film, so the mechanical destructive is the preferred method of treating film.

However, film structure is conducive to the electrical side, Wagar and Holm have made detailed description, are briefly summarized as follows. An electric field across an insulator or a high impedance film will lead to new mechanism, such as a bridge, can provide fritting body, with a critical electric field causes the voltage across the oxide film is to achieve this purpose necessary condition. However, more cases of critical electric field ( or even the critical voltage ) is also dependent on a previously mentioned variable factors: surface oxide film thickness, composition and structure. In addition, when the bridge after the emergence of resistance, the bridge also depend on the size of the current. The resistance can be changed with the voltage requirements may change will cause the surface oxide electronic fault and gives a general electronic application in trouble.